Many small lightweight clamping devices capable of controlling flow through tubes employed in intravenous systems and the like are well known in the art. These clamps most commonly include those, such as U.S. Pat. No. 3,942,228, where protrusions extending from upper and lower limbs precisely coincide, pressing down on the same point of the tube in order to control flow. Other clamps, such as U.S. Pat. No. 4,235,412, employ a single protrusion on the lower limb, which fits between two protrusions on an upper limb in order to restrict flow.
It has been found that neither of these modes maximizes efficiency in cutting off the flow through these flexible tubes. It has been discovered that the maximization of fluid cut-off by a clamp will occur when the upper and lower protruding clamping elements do not precisely coincide, but end up alongside each other when the clamp is closed, as pressure is put on the tube at two slightly separate points.